Aeroplane



IE. E. ANU WJ. HUFIFAKER.

AEROPLAFJE.

APPucAloN FILED 10h24, 1920.

194351,@349, V mmm Nw. M9 w22.`

nnwnnn c. Hurrsnnia nun Bonner iu. nurrnnna, or onocnnr, frnnnnssnn.

'Annorrann Application 'filed November 211, 1920. Serial No. 426,209.

Re it known that we,y EDWARD (luminous Hurmnun and Roennr ltlonnmun Hun FAKER, of Cbuckey, Tennessee, have invented an lfmpix'ivenient in ."tero1, `lanes, of which the following description, 'in connection with the accompanying drawings, is a specification, like characters on the drawings representing like parts.

rllhis invention aims to Yprovide novel and improved means for promoting automatic lateral and longitudinal stability of aeroplanes of all kinds in iiight. lt is applicable to monoplanes, biplanes, triplanes and the like, and togliders, toy aeroplanes,`flying torpedoes andfpower operated 'aircraft either with or without a pilot on board.

rlhe invention comprises shaping and arranging the lifting surfaces and head resistance, or one or vmore of them, with reference to the center of gravity of the craft so kas to tend to maintain an e'ven keel and straight line flight under the constantly changing air conditions normallyprevalent in the atmosphere.

Further objects and characteristics of the invention appear in connection with the following description. One embodiment of the invention is shown in the accompanying drawings, which 'is selected as a preferred form for illustrating the principles and mode of operation of the invention, but our invention is not restricted to this embodiment nor to aeroplanes of the single plane type.

ln the drawings, Fig. .1 is a top view of a glider embodying one form of the invention;

Figs. 2 and 3 are front vView and end view, respectively, of the same;

Fig. 4 is a cross section of the saine, on the line eee-4 in Fig. l; and

Fig. is a diagram showing the orosssectional shape of a supporting plane and the relative position with reference thereto of the center of gravity of the aeroplane structure, and the directions and points of application of the principal forces acting onv the plane and other parts of the structure, the cross-section being taken on the line 5-'-5 in Fig. 1.

Referring to the figures, the structure cornprises support-ing Aplane or wing 11, substantially rectangular in plan, covered Vwith a suitable fabric 12, and having a large poi`l tion of its lower surface Hat. The embodiment shown 'has a single supporting plane with all structural framework arranged above its supporting surface and the ends 13 are square. For the best results vertical stabilizers 111 are disposed at theends of the plane near its leading edge. These stabilizers project above the supporting surface.

rlhe fabric is stretched between the front and rear frame bars 15, 16, lwhich are stiffened by ribs 17. The middle ribs 18 are stren'thened to provide a Vsupport for an operator or for a motor in case one is provided. A transverse supporting bar or frame 19 passes through and is secured in the middle ribs 18 at a point approximately coincident with the center of gravity of the entire structure. This bar carries an adjustable weight 2() which may be secured a't such a place as to bring the center of gravity of the structure midway between the ends of thev plane.

rlhe center of kgravity of the plane structure for the best results should be located at a point about one-third or less of its width back from the leading edge, as shown by the line A-A in Fig. 5. rlFhis may be accomplished by weights 21 suitably disposed on the ribs 1S, or by adjusting the point of attachment of the load when the plane is utilized as a carrier.

The front edge portion 22 of the lifting surface is rounded or turned up to bring the leading edge into the plane of the top surface of the frame across the entire spread of the supporting plane; and the trailing edge 23 is rounded or turned up in a similar manner, as shown in' Figs. 5%, 4. and 5.

The center of pressure on the lifting surface of the plane is approximately in vertiV4 cal alineinent with the center of gravity of the aeroplane under normal. flying condi tions, and the line of pressure passes to the rear of the transverse bar 19, as shown by the line B-B in Fig. 5. rlhe resultant of the head resistance of the upturned leading edge of the plane is above the axis of the bar 19, as shown by the line C-C in Fig. 5v.

The point of application of the resultant pressure on the under surface of the wing varies with the angle of incidence, being nearer the leading edge the less the angle; and the head resistance varies with the speed of flight, being more than proportionally greater at high speeds than at lower speeds.

'lihcaeroplane adjusts itself autoinatically to maintain itself on an even keel for all speeds and conditions of flight by rockingslightly to vary the angle of incidence. If the speed is increased the aeroplane will ascend, and if it is decreased the aeroplane will descend.

'lhe automatic action of the aeroplane to maintain stability in flight is due to the shape of the lifting surfaces and the relative position of their center of pressure and head resistance with reference to the center of gravity of the aeroplane. By reference to Fig. 5 itis seen that the resultant B--B of the lifting force on the bottom surface passes slightly to the rear of the center of gravity of the aeroplane, thereby tending to depress the leading edgeof the plane. On the other hand, the resultant C-C of the head resistances of the leading edge and superstructure passes above the center of gravity and 'tends to raise the leading edge of the plane. These two forces balance each other under normal flying conditions. If for any reason the pressure of the air on the under surface of the plane should fall off through a change in the atmospheric conditions, as by striking a descending air current, the head resistance would then overbalance the resultant lifting force and would rock the plane to raise the leading edge and increase the angle of incidence, thereby increasing the lifting force and shifting its point of application slightly to the rear, resulting in increasing its moment about the center of gravity and restoring equilibrium.

Lateral stability `is automatically maintained by inertia and centrifugal force acting on the aeroplane structure, both of which are effective on the plane along the line of the center of gravity, and, as the center of gravity is above the lifting surface, these forces tend to counteract the tendency to bank and turn caused by the dropping of one side or lifting of the other side of the plane due to encountering irregular air cur rents or pockets. The higher the speed the greater the effect of centrifugal. force in maintaining lateral stability and in holding the aeroplane on a straight course.

Side slip causes an increase 'in the bead. rc-l sistance on the leading edge of the slipping side tending both to increase the angle of incidence and to turn the plane and thereby bring into play the effect of inertia and cen trifugal force to elevate the slipping side. Also the center of pressure on the underside of the plane will be shifted slightly toward the slipping side thereby increasing the force acting to elevate 1 c5 The invention is notrestricted to the parlasasae ticular embodiment herein shown, it being understood that the lifting surface, supporting plane,'and other elements of aeroplane structure described above are merely illus trative designs to enable the invention to be understood and applied to any type of aircraft wherein the promotion of automatic stability in flight is an object.

We claim the following as our invention:

l. An aeroplane having a substantially flat supporting surface arranged below its center of gravity with its leading edge curved upwards and projecting above said center of gravity whereby the head resistance on said supporting surface is above said center of gravity in normal flight.

2. An aeroplane having a supporting surface comprising a lifting area arranged below and to the rear of its center of gravity, and a convexedly curved area adjacent its leading edge and projecting above said center of gravity whereby the head resistance on said supporting surface is above and'in front of said center of gravity in normal flight. j

3. An aeroplane presenting surfaces for the action of dynamic forces due to motion through the air to promote automatic stability, said dynamic forces operating on the supporting surfaces and non-supporting surfaces respectively, said supporting surfaces being disposed below said nonsupporting surfaces whereby the head resistance upon said surfaces is centered above the center of lifting pressure thereon and tends to increase the angle of incidence of the leading edge when the speed increases in flight.

t. An aeroplane having a wide lateral spread of wing surface in `proportion toits longitudinal spread, said wing surface being disposed below the center of gravity of the aeroplane across its entire lateral spread on its principal lateral aXis, and having an upturned leading edge projecting above said center of gravity in normal flight.

5. An aeroplane having a wide lateral spread of wing surface in proportion to its longitudinal spread, said wing surface being disposed below the center of gravity of the aeroplane on its principal lateral axis, and having an upturned leading edge projecting above said center of gravity in normal flight, whereby the head resistance thereon is applied above the horizontal plane through said center of gravity.

6. An aeroplane comprising a substantially rigid supporting plane provided 'with upturned leading and trailing edges, and a superstructure carried thereby, the center of gravity of said aeroplane being above the center of lifting pressure.

7. An aeroplane comprising a substam Itiailly rigid supporting plane provided with upturned leading and trailing edges, and a superstructure carried thereby, the: center of gravity of said aeroplane being above the gravity above the center of lifting pressure center of lifting pressure and vertical stafor promoting automatic stability of said 10 bilizers projecting above the ends of said aeroplane. supporting plane. In testimony whereof, we have signed our 8. An aeroplane having a substantially names to this speciication. rigid frame, a supporting plane immovably secured to said frame, said aeroplane having EDWARD C. HUFFAKE-R. its center of head resistance and center of ROBERT M. HUFFAKER. 

